MIC2589_05 Datasheet, PDF (24/29 Pages) Micrel Semiconductor – Single-Channel, Negative High-Voltage Hot Swap Power Controller/Sequencer

Micrel
of the t_FLT, and read up the Y-axis scale to find the
intersection of the Single Pulse curve. This point is
the normalized transient thermal impedance (Z_θ(J-C)),
and the effective transient thermal impedance is the
product of R_θ(J-C) and the multiplier, 0.9 in this
example. Solving Equation 3,
T_J(transient) = (201.6W) × (0.4°C/W) × 0.9 = 72.6°C
MIC2589/MIC2595
Finally, add this result to the maximum steady state
junction temperature calculated previously to
determine the estimated maximum transient junction
temperature of the MOSFET: T_J(max.transient) =
74°C + 72.6°C = 146.6°C, which is safely under the
specified maximum junction temperature of 200°C for
the SUM110N10-09.
Figure 8. Transient Thermal Impedance – SUM110N10-09
December 2005
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M9999-120505
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